Richard:

We ARE getting esoteric--but the fundamental statement I disagreed with was that the water needed time to be heated by slowing down the panel. In practical terms, day to day use of solar panels or motorcycle engines this is at best misleading, at worst, just wrong.

but if your body's temperature dropped to the same as the wind temperature, then all the wind in the world won't lower your temperature any more.

I accept this as true only if you accept that the body's metabolism is irrelevant. Because, as EVERY kid who ever got out of a pool wet knows, the wind can chill you even THOUGH the air temp is higher than your skin...More importantly, an engine (which doesn't sweat) won't be cooled if the air is as hot as the engine. Evaporation of course causes cooling.

You can't get more energy out of the panel than is being given to it by the sun. If you get 90% of it at 8 GPM, then that is plenty. It's not worth all the problems of higher flow rates with their extra losses in friction through the pipes and cost of electricity for pumps to try and get much more than that.

This is absolutely a true statement--I have discussed friction as a limiting factor.

An interesting question about why my panels are in serial, rather than parallel. It's a practical matter. The FantaSea pool system uses the deck as the solar panels. They are 2x4 panels that surround the pool, and you walk on them...they therefore can only practically can be connected serially. In parallel would involve SO much piping as to be both impractical, and highly ugly. My better half made clear a condition of the pool was that it must be nice to look at

Here's the deck:


You can see the deck, but it's also the solar panels, so they are hidden in plain sight!

Here you can see that if there were a lot of hoses hanging down and joining into a bus hose or manifold, it would look hideous. Even the one hose to the controls on the left is unappealing.





I stand corrected on the increase of efficiency curve.

However, in practical terms, you do want to maximize flow through your system. My rules of thumb still hold:
1) If the water coming from the panels is warmer than than the pool, it's working, even if it's only one degree.
2) Practically speaking, on the hottest day, if your panel(s) are very hot, you aren't using them efficiently. They should be moving enough water to keep them almost as cool as the pool.
3) More flow is better than less, because...
4) It's BTUs that matter, not temperature. You want heat energy to heat your water. Usually, the more water you flow, the more BTUs you get, even if the water from the panels is a little cooler.
5) If your panels are leaking, you are pushing them too hard! (experience talking)
6) This may be beautiful but it has nothing to do with pools!